The present proposal will elucidate the potential mechanisms by which the neuropeptide arginine vasotocin (AVT) affects the expression of sexual behavior in male roughskin newts. It is hypothesized that this molecule exerts it's behavioral influence by acting as a central neuromodulator and influencing responsiveness to specific sexual stimuli. This will be tested by measuring behavioral and electrophysiological responses toward sexual stimuli presented within isolated sensory modalities (eg, visual, chemosensory, somatosensory) in response to brain AVT manipulations. Additionally, the AVT neural pathways involved in generating this neruopeptides effects upon sensory responsiveness will be determined. These studies will advance our understanding of the mechanisms by which neuropeptides influence the expression of behavior in vertebrate animals, perhaps even in our own species.